This discussion is confined to the process of deducing temperature of the atmosphere from observations of thermal radiation emitted by gases of the atmosphere; presently the most productive method of remote measurement of atmospheric temperature. This technique has evolved through experiments on three satellites of the Nimbus series (Wark, 1970; Hanel and Conrath, 1970; Smith et al., 1974) and is currently in operational use aboard the NOAA series of satellites. There are other methods of remotely sensing temperature, such as Raman backscatter (Strauch, Derr and Cupp, 1971) or molecular density measurements from. Rayleigh Scattering (Elterman, 1953), but they are not considered here.
Harold W. Yates,
"Limitations And Prospects For Atmospheric Sounding", Proc. SPIE 0051, Scanners and Imagery Systems for Earth Observation, (1 March 1974); doi: 10.1117/12.964552; https://doi.org/10.1117/12.964552